Methods and systems for utilizing 3D sensors in nuclear medicine

ABSTRACT

Described are methods and systems for scanning at least a portion of a patient with a gamma detector mounted on an arm extending towards the patient. One described method includes: obtaining data indicative or coordinates of points on the outer surface of the patient; determining a target position for the gamma detector based on the data indicative, of the coordinates; and causing the gamma detector to detect gamma radiation from the patient when the gamma detector is at the target position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/321,791 filed Jan. 29, 2019, now U.S. Pat. No. 11,020,074 issued Jun.1, 2021, which is the U.S. national phase of PCT Application No.PCT/EP2017/069832 filed on Aug. 4, 2017, which claims the benefit ofU.S. Provisional Patent Application No. 62/371,850 filed on Aug. 8,2016, the disclosures of which are incorporated in their entirety byreference herein.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to methodand system of imaging and, more particularly, but not exclusively, tomethod and system of medical imaging.

Volumetric scans such as SPECT scans, PET scans, CT scans, MRI scans,Ultrasound scans, and the like are commonly used, mostly in the medicalindustry, to observe the inner parts of objects that would otherwise beunobservable non-destructively. A conventional volumetric scan isintended to produce a volumetric image of a volume of the body.

SUMMARY OF THE INVENTION

Some embodiments of the present invention include a method of scanningat least a portion of a patient with a gamma detector mounted on an armextending towards the patient. The method comprising:

obtaining data indicative of coordinates of points on the outer surfaceof the patient;

determining a target position for the gamma detector based on the dataindicative of the coordinates; and

causing the gamma detector to detect gamma radiation from the patientwhen the gamma detector is at the target position.

In some embodiments, the arm extends along a specified direction, andobtaining the data comprises obtaining data indicative of a distancebetween the gamma detector and a point on the outer surface of thepatient along the specified direction.

In some embodiments, the method includes causing the detector to move tothe target position.

In some embodiments, causing the detector to move to the target positioncomprises causing the arm to extend towards the patient.

In some embodiments, determining a target position comprises determininga plurality of target positions for the gamma detector.

In some embodiments, the method includes causing the detector to movefrom one of the plurality of target positions to the other.

In some embodiments, the method includes causing the detector to movefrom one of the plurality of target positions to the other and detectgamma radiation during the movement.

In some embodiments, causing the gamma detector to detect gammaradiation from the patient comprises causing the gamma detector todetect gamma radiation from the patient at each of the plurality oftarget positions determined.

In some embodiments, determining a plurality of target positionscomprises determining a range of directions from which the arm extendstowards the patient.

In some embodiments, the method may include moving the gamma detectorcontinuously along said range of directions, and causing the gammadetector to detect gamma radiation during said moving.

In some embodiments, determining the target position comprisesdetermining a target swivel angle between said detector and the arm onwhich the detector is mounted.

In some embodiments, causing the gamma detector to detect gammaradiation from the patient at the target position comprises causing thegamma detector to change a swivel angle between the detector and the armon which the detector is mounted.

In some embodiments, determining the target position comprisesdetermining a target direction for the arm to be extended towards thepatient.

In some embodiments, the method includes causing a change in thedirection along which the arm is extended and detect gamma radiationfrom a plurality of directions.

In some embodiments, the target position determined is characterized bya target distance between the detector and the patient along the targetdirection.

Some embodiments of the present invention include a method of scanningat least a portion of a patient with a gamma detector mounted on an armextending towards the patient along a specified direction, the methodcomprising:

obtaining data indicative of a distance between the gamma detector andthe patient along said specified direction;

determining a target direction for the arm based on the data indicativeof the distance;

causing the arm to move to the target direction;

obtaining data indicative of a distance between the gamma detector andthe patient along said target direction;

determining a target position for the gamma detector based on the dataindicative of the distance along the target direction; and

causing the gamma detector to detect gamma radiation from the patient atthe target position.

In some embodiments, determining the target position comprisesdetermining a target distance between the detector and the patient alongthe specified direction.

In some embodiments, obtaining the data indicative of the distancecomprises obtaining data received from at least one 3D sensor.

In some embodiments, the scanning of the at least a portion of thepatient is with two or more gamma detectors, each mounted on arespective arm extending towards the patient along a respectivespecified direction, and the method includes:

obtaining for each of the gamma detectors data indicative of a distancefrom the patient along the respective specified direction;

determining for each of the gamma detectors a respective target positionbased on the data indicative of at least some of the distances; and

causing each of the gamma detectors to detect gamma radiation from thepatient at the respective target position.

In some embodiments, the scanning of the at least a portion of thepatient is with two or more gamma detectors supported by a commongantry, and causing a gamma detector to detect gamma radiation from thepatient at a target position comprises rotating the gantry.

In some embodiments, the scanning of the at least a portion of thepatient is with two or more gamma detectors supported by a commongantry, and causing a gamma detector to detect gamma radiation from thepatient at a target position comprises moving the patient in respect tothe gantry and/or moving the gantry in respect to the patient.

In some embodiments, determining a target position for the gammadetector comprises generating an approximation to the outer surface ofthe patient based on the data indicative of the distance between thegamma detector and the patient along the specified direction.

In some embodiments, the gamma detectors are caused to detect the gammaradiation from the patient simultaneously at the respective targetpositions.

In some embodiments, each gamma detector is in a respective detectionhead, and the target position of each gamma detector is determined inconsideration of target positions of other gamma detectors to ensurethat the detection heads do not collide with each other.

In some embodiments, the method includes receiving data indicative ofthe kind of image to be taken, and wherein the target position for thegamma detector is determined based on the data indicative of thedistance and the data indicative of the kind of image to be taken.

Some embodiments of the present invention may include an apparatus forscanning at least a portion of a patient, the apparatus comprising:

a gamma detector mounted on an end of an arm extending towards thepatient support along a specified direction;

a patient support; and

a processor configured to:

-   -   obtain data indicative of a distance between the gamma detector        and the patient along said specified direction;

determine a target position for the gamma detector based on the dataindicative of the distance; and

cause the gamma detector to detect gamma radiation from the patient atthe target position.

In some embodiments, the arm is extendible.

In some embodiments, the processor is configured to determine aplurality of target positions for the gamma detector.

In some embodiments, the processor is configured to cause the gammadetector to detect gamma radiation from the patient at each of theplurality of target positions.

In some embodiments, the plurality of target positions include a rangeof directions from which the arm extends towards the patient.

In some embodiments, the processor is configured to cause the gammadetector to move continuously along said range of directions and detectgamma radiation during the movement.

In some embodiments, the target position comprises a target swivel anglebetween the detector and the arm.

In some embodiments, the processor is configured to cause the gammadetector to change a swivel angle between the detector and the arm basedon the data indicative of the distance.

In some embodiments, the processor is configured to determine, based onthe data indicative of the distance, a target direction for the arm.

In some embodiments, the processor is configured to cause a change inthe direction along which the arm is extended based on the dataindicative of the distance.

In some embodiments, the processor is configured to determine based onthe data indicative of the distance a target distance between thedetector and the patient along the target direction.

In some embodiments, the processor is configured to determine a targetdistance between the detector and the patient along the specifieddirection.

In some embodiments the processor is configured to obtain the dataindicative of the distance by processing data received from at least one3D sensor.

In some embodiments, the apparatus further includes the at least one 3Dsensor.

In some embodiments, the apparatus includes two or more gamma detectors,each mounted on a respective arm extending towards the patient along arespective specified direction, and wherein the processor is configuredto:

obtain, for each of the gamma detectors, data indicative of a distancefrom the patient along the respective specified direction;

determine, for each of the gamma detectors, a respective target positionbased on the data indicative of the distances; and

cause each of the gamma detectors to detect gamma radiation from thepatient at the respective target position.

In some embodiments, the apparatus includes two or more gamma detectorssupported by a common gantry, and the processor is configured to causethe gantry to rotate to allow a gamma detector to detect gamma radiationfrom a direction different from the respective specified direction.

In some embodiments, the apparatus includes two or more gamma detectorssupported by a common gantry, and the processor is configured to causemovement of the patient support in respect to the gantry and/or causemovement of the gantry in respect to the patient support based on thedata indicative of the distance.

In some embodiments, the processor is configured to generate anapproximation to the outer surface of the patient based on the dataindicative of the distance between the gamma detector and the patientalong the specified direction, and determine the target position basedon the approximation.

In some embodiments, the processor is configured to cause the gammadetectors to detect the gamma radiation from the patient simultaneouslyat the respective target position.

In some embodiments, each gamma detector is in a respective detectionhead, and the processor is configured to determine the target positionof each gamma detector considering target positions of other gammadetectors to ensure that the detection heads do not collide.

In some embodiments, the processor is configured to receive dataindicative of the kind of image to be taken, and determine the targetposition for the gamma detector based on the data indicative of thedistance and the data indicative of the kind of image to be taken.

An aspect of some embodiments of the invention includes a system formedical imaging a region of interest. A region of interest may also bereferred to herein as a region to be imaged. The system may include:

a support, for supporting at least a portion of a patient's body;

a gantry, supporting a gamma detector,

a 3D sensor; and

a processor,

wherein

the processor is configured to:

determine a region to be imaged;

receive from the 3D sensor coordinates of at least one point of an outersurface of the patient, the support, or both the patient and thesupport; and

determine at least one parameter affecting an arrangement of the gammadetectors in respect to the region to be imaged based on the coordinatesof the at least one point.

In some embodiments, the at least one parameter comprises a position ofthe support in respect to the gantry.

In some embodiments, the at least one parameter comprises a gantry angleof a gantry supporting the detectors.

In some embodiments, the at least one parameter comprises a plurality ofgantry angles.

In some embodiments, the processor is further configured to determine,based on the indication of the kind of image to be taken and thecoordinates of the at least one point, a dwelling time for each of saidplurality of gantry angles.

In some embodiments, the at least one parameter comprises a range ofgantry angles.

In some embodiments, the processor is further configured to determine,based on the indication of the kind of image and the coordinates of theat least one point, a pace for moving the gantry along the range ofgantry angles.

In some embodiments, the processor is configured to determine, based onthe indication of the kind of image and the coordinates of the at leastone point, a plurality of different paces, each for moving the gantryalong a sub-range of the range of gantry angles.

In some embodiments, each of said gamma detectors is mounted on an armextendable from the gantry.

In some embodiments, each of said gamma detectors is arranged to swivelin respect to an arm connecting the gamma detector to the gantry.

In some embodiments, the at least one parameter includes a swivel angleof the detector in respect to the arm for at least one of the detectors.

In some embodiments, the at least one parameter includes a plurality ofswivel angles of the detector in respect to the arm for at least one ofthe detectors.

In some embodiments, the at least one parameter includes a range ofswivel angles of the detector in respect to the arm for at least one ofthe detectors.

In some embodiments, the processor is further configured to determine,based on the indication of the kind of image and the coordinates of theat least one point, a pace for moving the detector along the range ofswivel angles.

In some embodiments, the at least one parameter includes an amount ofextension of at least one extendable arm connecting a gamma detector tothe gantry.

In some embodiments, the processor is configured to generate, based onthe coordinates of the at least one point, a model of the outer surfaceof the patient, the support, or both the patient and the support, anddetermine the at least one parameter based on a location of the regionto be imaged in respect to the model.

In some embodiments, the processor is configured to determine the atleast one parameter affecting the arrangement of the gamma detectors inrespect to the region of interest based on a location of the region ofinterest in respect to the model of the outer surface of the patientand/or support.

An aspect of some embodiments of the inventions includes a method ofimaging a region of interest in a patient by a medical imaging devicefor imaging a patient supported by a patient support, the medicalimaging device comprising a gantry and a plurality of gamma detectorssupported on the gantry, the method comprising:

receiving an indication of the kind of image to be taken;

receiving coordinates of at least one point of an outer surface of thepatient, the support, or both the patient and the support;

determining at least one parameter affecting an arrangement of the gammadetectors in respect to the region of interest based on the indicationof the kind of image and the coordinates of the at least one point; and

controlling the gamma detectors, the gantry, and/or the support inaccordance with the at least one parameter determined.

In some embodiments, the at least one parameter comprises a position ofthe support in respect to the gantry.

In some embodiments, the at least one parameter comprises a gantry angleof a gantry supporting detectors in respect to an axis of the gantry.

In some embodiments, the at least one parameter comprises a plurality ofgantry angles.

In some embodiments, the method includes determining, based on theindication of the kind of image to be taken and the coordinates of theat least one point, a dwelling time for each of said plurality of gantryangles.

In some embodiments, the at least one parameter comprises a range ofgantry angles.

In some embodiments, the method includes determining, based on theindication of the kind of image to be taken and the coordinates of theat least one point, a pace for moving the gantry along the range ofgantry angles.

In some embodiments, each of said gamma detectors is mounted on an armextendable from the gantry.

In some embodiments, each of said gamma detectors is mounted on an armextendable from the gantry so that the gamma detector may swivel inrespect to the arm.

In some embodiments, the at least one parameter includes a swivel angleof the detector in respect to the arm for at least one of the detectors.

In some embodiments, the at least one parameter includes a plurality ofswivel angles of the detector in respect to the arm for at least one ofthe detectors.

In some embodiments, the at least one parameter includes a range ofswivel angles of the detector in respect to the arm for at least one ofthe detectors.

In some embodiments, the method further includes determining, based onthe indication of the kind of image and the coordinates of the at leastone point, a pace for moving the detector along the range of swivelangles.

In some embodiments, n the at least one parameter includes an amount ofextension of at least one extendable arm connecting a gamma detector tothe gantry.

In some embodiments, the method includes generating, based on thecoordinates of the at least one point, a model of the outer surface ofthe patient, the support, or both the patient and the support, anddetermining the at least one parameter based on a location of the regionto be imaged in respect to the model.

In some embodiments, the method includes determining the at least oneparameter affecting the arrangement of the gamma detectors in respect tothe region of interest based on a location of the region of interest inrespect to the model of the outer surface of the patient and/or support.

Some embodiments of the present invention includes a system forperforming medical imaging of a region of interest, the systemcomprising:

a support for supporting at least a portion of a patient's body;

a gantry which supports multiple gamma detectors;

a 3D sensor configured to sense a point of an contour of a portion ofthe patient; and

a processor configured to determine a desired position of the support inrespect to the gantry based on data obtained by the 3D sensor.

In some embodiments, the processor comprises:

-   -   an input configured to receive data indicative of an contour of        at least a portion of the patient sensed by the 3D sensor;    -   a memory storing instructions for determining a desired position        of the support in respect to the gantry based on the data        received by the input; and    -   an output.

In some embodiments, the output is configured to indicate to a user adesired position determined by executing the instructions.

In some embodiments, the output is configured to control the position ofthe support in respect to the gantry based on a desired positiondetermined by executing the instructions.

In some embodiments, the system includes a user interface allowing auser to indicate a kind of scan to be performed, wherein the processoris configured to determine the desired position of the support inrespect to the gantry based on results obtained by the 3D sensor and thekind of scan indicated by the user.

In some embodiments, the 3D sensor is installed on said gantry.

In some embodiments, the desired position of the support in respect tothe gantry includes a vertical position of the support in the gantry.

In some embodiments, the desired position of the support in respect tothe gantry includes a horizontal position of the support in the gantryalong a longitudinal axis of the patient.

In some embodiments, the processor is configured to determine thedesired position of the support in respect to the gantry based on:

results obtained by the 3D sensor, and

a non-diagnostic scan of a portion of the patient scanned by the system,said portion comprising the region to be imaged.

In some embodiments, the 3D sensor is configured to generate a pointcloud indicative of the position of an contour of a portion of thepatient, the support, or both the patient and the support.

In some embodiments, the 3D sensor is one of a plurality of 3D sensors,and the processor is configured to determine the desired position of thesupport in respect to the gantry based on data obtained by the pluralityof 3D sensors.

In some embodiments, the processor is configured to estimate anapproximate contour of the patient and the support based on input fromthe plurality of 3D sensors.

Some embodiments of the present invention include a method ofautomatically determining a desired position of a support carrying apatient in respect to a gantry that supports multiple gamma detectorsfor imaging the patient, the method comprising:

receiving from a user interface indication of a portion of the patientto be scanned;

receiving, from at least one 3D sensor, data indicative of spatialcoordinates of a contour of the patient and the support; and

determining the desired position of the support based on the indicationand the data.

In some embodiments, the method further includes:

receiving through the user interface an instruction to bring the supportto the desired position determined; and

controlling the support to move to the desired position determined inresponse to receiving the instruction.

In some embodiments, determining the desired position of the supportcomprises combining the data received from the 3D sensor with anon-diagnostic image data of a portion of the patient supported by thesupport.

In some embodiments, the method includes:

scanning a portion of the patient supported by the support to obtainnon-diagnostic image data of said portion of the patient; and

combining the data received from the 3D sensor with the non-diagnosticimage data to determine the desired position of the support.

In some embodiments, the method includes

sending a control signal to the at least one 3D sensor to collect datapertaining to the patient on the support, and

determining the desired position of the support based on a point cloudindicative of the position of a contour of a portion of the patientproduced in response to said control signal.

Some embodiments of the invention include a system for generating ascanning plan for medical imaging of at least a portion of a patient,the system comprising:

a support for supporting at least a portion of a patient's body;

a gantry which supports multiple gamma detectors;

at least one 3D sensor configured to sense at least one point of anouter surface of a portion of the patient; and

a processor configured to receive information comprising:

-   -   an indication of a region to be imaged; and    -   data indicative of the location of the at least one point sensed        by the at least one 3D sensor, and

generate a scanning plan for the medical imaging based on informationreceived.

In some embodiments, the at least one 3D sensor is configured togenerate a point cloud indicative of the position of an outer surface ofat least one of: a portion of the patient, a portion of a supportsupporting the patient during the medical imaging, or portions of boththe patient and the support.

In some embodiments, the system includes a plurality of 3D sensors, andthe processor is configured to generate the scanning plan based on datasensed by the plurality of 3D sensors.

In some embodiments, the processor is configured to estimate anapproximate contour of the patient and the support based on input fromthe at least one 3D sensor.

In some embodiments, the processor comprises:

-   -   an input configured to receive data indicative of at least one        point of an outer surface of at least a portion of the patient        sensed by the at least one 3D sensor; and    -   a memory storing instructions for generating the scanning plan        based on the data received by the input.

In some embodiments, at least one of the at least one 3D sensor isinstalled on said gantry.

In some embodiments, each of the gamma detectors is connected to thegantry by an extendable arm so that the detector can swivel in respectto the extendable detector arm.

In some embodiments, the scanning plan includes a number of gantrypositions and corresponding gantry angles.

In some embodiments, the scanning plan includes a dwell time for each ofsaid gantry positions, at least two of said dwell times being differentfrom each other.

In some embodiments, the scanning plan includes a plurality of swivelangles for at least one of the detectors.

In some embodiments, the scanning plan includes a dwell time for each ofsaid swivel angles, at least two of said dwell times being differentfrom each other.

In some embodiments, the scanning plan includes a first and secondgantry positions and a rate of advancing the gantry between said firstand second gantry positions.

In some embodiments, the scanning plan includes a plurality of rates,each of advancing the gantry along a portion of a path between the firstand second gantry positions.

In some embodiments, the scanning plan includes a positioning of thesupport in respect to the gantry.

In some embodiments, the system includes a user interface configured toreceive from a user indication as to the kind of scan to be planned, andthe processor is configured to generating the scanning plan based onsaid indication and the input from the at least one 3D sensor.

Some embodiments of the present invention include a method of planning ascan of a region residing in a portion of a patient by a medical imagingdevice comprising a support at least for the portion of the patient anda gantry supporting multiple gamma detectors, the method comprising:

receiving, from a 3D sensor, data pertaining to spatial coordinates of apoint of an outer surface of the portion of the patient;

receiving a non-diagnostic image of the portion of the patient;

receiving indication to a region of special interest within the regionimaged in the non-diagnostic image;

and

planning the scan based on the location of the region to be imaged andthe region of special interest in respect to the contour of the patient.

In some embodiments, receiving from the 3D sensor data pertaining tospatial coordinates of points composing a point cloud indicative of theposition of an contour of a portion of the patient, the support, or boththe patient and the support.

In some embodiments, receiving data from a plurality of 3D sensors,planning the scan based on data obtained by the plurality of 3D sensors.

In some embodiments, the method includes estimating an approximatecontour of the patient and the support based on input from the pluralityof 3D sensors.

In some embodiments, the 3D sensor is installed on the gantry.

In some embodiments, each of the gamma detectors is connected to thegantry by an extendable detector arm so that the detector can swivel inrespect to the extendable detector arm.

In some embodiments, the planning includes determining a number ofgantry positions and corresponding gantry angles.

In some embodiments, the scanning plan includes a dwell time for each ofsaid gantry positions, at least two of said dwell times being differentfrom each other.

In some embodiments, the detectors are configured to swivel, and thescanning plan includes a plurality of swivel angles for at least one ofthe detectors.

In some embodiments, planning the scan comprises determining a dwelltime for each of said swivel angles, at least two of said dwell timesbeing different from each other.

In some embodiments, the scanning plan includes a first and secondgantry positions and a rate of advancing the gantry between said firstand second gantry positions.

In some embodiments, the scanning plan includes a first and secondswivel angle for at least one detector and a rate of advancing thedetector between said first and second swivel angles.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

Implementation of the method and/or system of embodiments of theinvention can involve performing or completing selected tasks manually,automatically, or a combination thereof. Moreover, according to actualinstrumentation and equipment of embodiments of the method and/or systemof the invention, several selected tasks could be implemented byhardware, by software or by firmware or by a combination thereof usingan operating system.

For example, hardware for performing selected tasks according toembodiments of the invention could be implemented as a chip or acircuit. As software, selected tasks according to embodiments of theinvention could be implemented as a plurality of software instructionsbeing executed by a computer using any suitable operating system. In anexemplary embodiment of the invention, one or more tasks are performedby a data processor, such as a computing platform for executing aplurality of instructions. Optionally, the data processor includes avolatile memory for storing instructions and/or data and/or anon-volatile storage, for example, a magnetic hard-disk and/or removablemedia, for storing instructions and/or data. Optionally, a networkconnection is provided as well. A display and/or a user input devicesuch as a keyboard or mouse are optionally provided as well.

As used herein, the term “processor” may include an electric circuitthat performs a logic operation on input or inputs. Whenever a processoris mentioned, it may be embodied in a single processor, or in aplurality of processors. A processor may include one or more integratedcircuits, microchips, microcontrollers, microprocessors, all or part ofa central processing unit (CPU), graphics processing unit (GPU), digitalsignal processors (DSP), field-programmable gate array (FPGA) or othercircuit suitable for executing instructions or performing logicoperations. The instructions executed by the processor may, for example,be pre-loaded into the processor or may be stored in a separate memoryunit such as a RAM, a ROM, a hard disk, an optical disk, a magneticmedium, a flash memory, other permanent, fixed, or volatile memory, orany other mechanism capable of storing instructions for the processor.The processor(s) may be customized for a particular use, or can beconfigured for general-purpose use and can perform different functionsby executing different software.

If more than one processor is employed, all may be of similarconstruction, or they may be of differing constructions electricallyconnected or disconnected from each other. They may be separate circuitsor integrated in a single circuit. When more than one processor is used,they may be configured to operate independently or collaboratively. Theymay be coupled electrically, magnetically, optically, acoustically,mechanically or by other means permitting them to interact.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1A is a flowchart of a method of scanning at least a portion of apatient according to some embodiments of the invention;

FIG. 1B is a diagram showing a portion of the patient, a gamma detector,a sensor, and some points and directions mentioned in the description ofFIG. 1A;

FIG. 1C is a diagrammatic illustration of a system for performingmedical imaging of a region of interest according to some embodiments ofthe invention;

FIG. 2 is a simplified block diagram of a processor configured to carryout methods described herein;

FIG. 3A and FIG. 3B are flowcharts of methods of imaging a region ofinterest in a patient according to some embodiments of the invention;

FIG. 3C is a flowchart of a method of determining a desired verticalposition of a patient support according to some embodiments of theinvention;

FIG. 4 is a diagrammatic illustration of a system with the patient atthe center of the gantry according to some embodiments of the invention;

FIG. 5 is a diagrammatic illustration of a system with the patient offthe center of the gantry according to some embodiments of the invention;

FIGS. 6A and 6B are two (mutually orthogonal) cross-sectionalillustrations of a gamma detector according to some embodiments of theinvention;

FIG. 7A is a flowchart of a method of determining gantry anglesaccording to some embodiments of the invention;

FIG. 7B is a diagrammatic illustration of a system with the patient offthe center of the gantry, with the detectors arranged differently thanin FIG. 5 , according to some embodiments of the invention;

FIG. 7C is a flowchart of a method for determining gantry anglesaccording to some embodiments of the invention; and

FIG. 8 is a flowchart of a method of planning a scan of a region to beimaged according to some embodiments of the invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION Overview

The present invention, in some embodiments thereof, relates to methodsand systems of imaging and, more particularly, but not exclusively, tomethods and systems of medical imaging.

In some embodiments of the invention, the imaging is single photonemission computed tomography (SPECT). In typical SPECT imaging, thepatient is administered with agents that emit gamma photons and bindpreferentially to specific tissues, and the image is acquired bydetecting gamma photons emitted from within a region in the body of thepatient, and assigning each of the detected photons a direction fromwhich it emerged, or a plurality of directions, each associated with aprobability that this is the direction from which the photon emerged.The data on received photons, emerging directions, and associatedprobabilities may be used for reconstructing an image of the region inthe body of the patient.

Assigning each of the detected photons a probability that it emergedfrom a specific direction may be accomplished using a collimator havingone side facing the imaged body, and another side facing a gammadetector. The collimator may include any structure that limits thedirections from which photons may arrive at the gamma detector. Forexample, a parallel hole collimator is a structure that includes a lotof parallel gamma absorbing partitions that define cells in betweenthem. The cells may have a rectangular cross-section, hexagonalcross-section, circular cross-section, or a cross section of any othershape. A gamma photon that hits one of those partitions is usuallyabsorbed in the partition, so that mainly photons that go in parallel tothe partitions, along a cell, reach the detector. This way, each photonthat reaches the gamma detector is associated with a high probability toemerge from a location along a line parallel to the collimator's cells,and lower probabilities to emerge from other directions. The specificprobabilities may depend on the size of cells, the thickness of thewalls, and the absorption coefficient of the wall. The gamma detectormay include a plurality of detection cells, e.g., one for everycollimator cell, so that the location at which the photon meets thedetector may also be known.

In some embodiments, there are many gamma detectors (e.g., 4, 5, 6, 8,12, 16, or intermediate number), each in a respective detection head. Adetection head may include a detector, electronics configured toindicate whenever a photon is received at the detector and where on thedetector the photon is received, and a collimator. The detection headsmay be supported on a frame (a/k/a gantry) carrying them. In someembodiments, there is a common frame, common to all the detection heads.In some embodiments, there may be two or more frames, each supportingone or more of the detection heads. During imaging, a portion of thepatient that has to be imaged is supported on a patient support, and thedetectors are brought as close as possible to the patient outer surfaceso as to allow for maximal possible resolution of the imagesreconstructed from the readings of the detector.

In some embodiments, the imaging may take place without a gantry. Forexample, the detectors may be mounted on separate arms that are notsupported on a common frame, but controlled to move cooperatively, sotheir movement to and from the patient brings each of the detectors to arequisite position in respect to the region to be imaged.

The exact arrangement of the detectors in respect to the region to beimaged may determine to a large extent the image resolution, and theintensity of radiation collected at a given imaging time.

An aspect of some embodiments of the invention includes scanning apatient by gamma radiation using data indicative of coordinates ofsurface points of the patient. For example, the data may be indicativeof a distance between a gamma detector and the patient. This distancemay be used for determining a target position for the detector, fromwhich it would be desired to detect the gamma radiation. In someembodiments, determining a target position for a gamma detector based ondata indicative of coordinates of one or more points on the outersurface of the patient and/or support may include determining a positionat which the distance between the detector and the patient (or support)outer surface is minimal, so as to be as close as possible to thepatient, while not touching the patient.

For example, if the gamma detector can approach the patient along somespecified direction, the target position may be along that direction, asclose as possible to the patient without touching the patient. Forexample, if the gamma detector is mounted on an arm extendable from agantry towards the patient, the specified direction may be the extensiondirection of the arm. If the current distance between the patient andthe detector is 30 cm, the target position may be 29 cm closer to thepatient, along the specified direction.

In some embodiments, it may be desirable to detect the radiation frommany different directions. In some embodiments, the number of differentangular positions from which gamma radiation is to be detected, and insome embodiments also the angular positions themselves may be determinedbased on coordinates of at least one point on a surface of the patient,or the patient and the support. For example, the coordinates of thesurface point(s) may be used to estimate an outer shape of the patientand support, and the number of angular positions (and the angularpositions themselves) may be determined so that gamma radiation iscollected from as many locations within the patient and in a sufficientnumber of direction to allow satisfactory reconstruction of the image(e.g., sufficient to span 180°) at minimal scanning time. Whilereference is usually made herein to at least one point on the surface,more than one point may be advantageous. For example, two, four, six, oreight points may usually allow better modelling of the outer surface,and therefore also better determination of target position of detectors,or other parameters to be determined for a scanning plan. Point cloudscomprising hundreds of points may even be better, in some embodiments.However, in some embodiments, the accuracy obtained from one point, forexample using a spatial model of the (or a typical) patient and/or thesupport, may be sufficient. The number of different angular positionsfrom which gamma radiation is to be detected, and the angular positionsthemselves, may depend on coordinates of points on the surface of thepatient. For example, such coordinates may be indicative of a cylinderthat has large enough a radius to encompass the entire patient portionto be imaged, but small enough to nearly touch the patient. Now, whenthis radius is large (e.g., for imaging the abdomen of a large patient),there may be a need to detect from more angular positions than when thisradius is small (e.g., for imaging a head or a knee of a patient). Thus,the coordinates of one target position may be indicative to the radiusof the cylinder, and be used to determine a number of target positionsfor the detector. It is noted that the cylinder in this example may bereplaced by any other shape that may be large enough to encompass thepatient portion to be imaged and small enough to nearly touch thepatient or the patient support.

In yet another example of scanning a patient using data indicative ofcoordinates of surface points of the patient, swivel angles may beconsidered. In some embodiments, the gamma detector is mounted on an armso that the detector can swivel around one or more axes attached to thearm to change the field of view of the detector without moving the arm.In some embodiments, the field of view encompasses all points of thepatient viewable from a given position of the arm. However, in somecases, swiveling the detector may bring into the field of view of thedetector areas outside the patient. Limiting the swivel only to anglesat which at least a portion of the patient is within the field of viewof the detector may save scanning time, and/or improve image qualityobtainable in a given scanning time. Thus, in some embodiments, thecoordinates of at least one point on the surface of the patient may beused to estimate the general shape of the patient and the support, forexample using a spatial model of the (or a typical) patient and/or thesupport, and swivel angles may be determined based on this estimate sothat the detectors swivel only through angles where at least a portionof the field of view is occupied by a portion of the patient. In someembodiments, this requirement may be more restrictive, for example, thatat least half of the field of view will have in it a portion of the ROI.This exemplifies a way by which information indicative of coordinates ofsurface points of the patient may be used to determine the limits of theswiveling of the detector.

In some embodiments, the scanning method may include obtaining dataindicative of the distance between the detector and the patient alongtwo or more directions. For example, in some embodiments, dataindicative of the distance between the patient and the detector may beobtained when the detector is aimed at the patient along a firstdirection (e.g., the direction referred to herein as a specifieddirection). Based on this data, it may be determined that detectionshould take place when the detector is aimed at the patient along asecond direction (e.g., the direction referred to herein as a targetdirection). Once the detector is at the second position, it sometimesmay be useful to obtain information indicative of its distance from thepatient along the second direction. While this information could have,in some embodiments, been estimated (e.g., approximated) based on thedata indicative of the distance between the detector and the patientalong the first direction, a measurement devoted for obtaininginformation indicative of the distance along the second direction may bemore accurate than the estimation made before. The new data may beuseful in determining a target position for the detector in greateraccuracy than could have been possible using the data obtained regardingthe distance along the first direction.

The data indicative of the distance between the detector and the patientalong the specified direction (or along any other direction) may beobtained from a 3D sensor, and may include data indicative ofcoordinates of one or more points on the outer surface of the patient.In some embodiments, the data may be obtained from a plurality of 3Dsensors. As more 3D sensors are employed, more data may be obtained in agiven time. For example, data obtained from a single 3D sensor moved tosense the patient from 6 different directions may be obtained by sixsensors at less than a sixth of the time, if the sensing is carried outsimultaneously from 6 directions, and time spent on moving a sensor fromone viewing direction to another is saved. In some embodiments, thesaving may be smaller because not all the sensors work together, to omitcross-talk problems or the like.

In some embodiments, the scanning may take place using a plurality ofgamma detectors. In some such embodiments, the gamma detectors detectthe gamma radiation from the patient simultaneously, each from arespective target position. In some embodiments, each gamma detector isin a respective detection head, and the target position of each gammadetector is determined in consideration of target positions of othergamma detectors to ensure that the detection heads do not collide witheach other.

Each gamma detector may be mounted on a respective arm that extendsalong a respective specified direction. In some embodiments, each armmay also be extendible along the respective specified direction, so asto get closer to the patient or away thereof along said direction. Insome embodiments, the target position for each of the detectors may bedetermined based on data indicative of distances between the patient andsome or all of the plurality of detectors. For example, in someembodiments, in determining a target position of a certain detector,data indicative of the distances of the patient from the neighboringdetectors, neighboring the certain detector, may be used.

In some embodiments, one, some, or each of the one or more gammadetectors involved in the scanning may have a respective 3D sensormounted near it. For example, the 3D sensor may be mounted on a gantrywhere the arm carrying the gamma detector is supported, so that the 3Dsensor is pointed at the patient along about the same direction as thegamma detector. In some embodiments, the field of view of each sensor issignificantly larger than that of a detector, so the exact direction atwhich the sensor is aimed is less crucial. In another example, a 3Dsensor may be mounted on the arm, e.g., inside a detection headcomprising the gamma detector.

In some embodiments, two or more of the gamma detectors used in themethod (for example, all of them) may be supported by a common gantry.In such embodiments, changing the angle from which a detector detectsgamma radiation may include rotating the gantry and/or moving thepatient in respect to the gantry.

In some embodiments, the determination of a target position for thegamma detector may include generating an approximation to the outersurface of the patient. The approximation may be based on dataindicative of coordinates of a plurality of points on the outer surfaceof the patient and/or based on data indicative of distances of thepatient from gamma detector(s) along a plurality of directions. Forexample, the approximation may provide approximated coordinates of anypoint of interest on the outer surface of the patient. Suchapproximation may be used for determining target position(s) to thegamma detector(s), for example, to determine limits for swiveling of thegamma detector(s), to determine a best position of the patient inrespect of the gantry, to decide on angles from which gamma radiation isto be collected, etc. For example, in some embodiments it may be desiredto have the center of the patient located at the center of the gantry(or shift from the center of the gantry by a predetermined amount). Thelocation of the patient may be determined based on data indicative ofcoordinates of at least one point on the outer surface of the patient byestimating where the center of the patient is. The desired location ofthe patient may then be determined so that the centers of the patientand the gantry overlap or shift from one another as required. Thedetermination or estimation of the location, for example the center, ofthe patient may include, for example, modeling the shape of the patientbased on the data indicative of coordinates of surface points. Themodeling may include, for example, interpolating and/or triangulatingbetween surface points to build a continuous surface that models theouter surface of the patient (or the patient and support), whether inthe context of center alignment or in any other context that requiresdetermination or estimation of the location of the patient.

In some embodiments, the target position(s) may be determined based ondata indicative of the kind of image to be taken, in addition to thedistance between the patient and the detector, the coordinate of a pointof the outer surface of the patient, or a combination of such distanceand coordinates. The kind of image may include, for example, a region ofinterest, an organ of interest, a dimensionality of the image (e.g., 2Dor 3D), etc. Examples to such embodiments are detailed below.

An aspect of some embodiments of the present invention may include anapparatus configured to carry out one or more of the scanning methodsdescribed herein. For example, the apparatus may include a gammadetector and a processor. The gamma detector may be mounted on an end ofan arm extending towards the patient along a specified direction. Insome embodiments, the arm may also be extendible along the specifieddirection. The processor may be configured to carry out a method asdescribed herein. For example, the processor may be configured to:obtain data, indicative of a distance between the gamma detector and thepatient along the specified direction. The data may be obtained from oneor more 3D sensor(s), which may form part of the apparatus. Theprocessor may be further configured to determine at least one targetposition for the gamma detector based on the data indicative of thedistance. The processor may be further configured to cause the gammadetector to move to each of the at least one target position, and whenat a target position, detect gamma radiation emitted from the patient.In some embodiments, the processor may be configured to move thepatient, e.g., by moving a patient support, on which the patient or aportion of the patient body is supported. The movement may be of thepatient in respect of the detector, of the detector in respect of thepatient, or the patient and detector may both move in respect to eachother.

An aspect of some embodiments of the invention includes automaticallydetermining how to arrange the detectors near the outer surface of thepatient to image a given region. In some embodiments, this automaticdetermination is based on data indicative of the region to be imaged,and a three dimensional approximation or model of the outer surface ofthe patient and the patient support (e.g., the patient and the bed).Throughout the specification, a bed is used as an example of a patientsupport, and a reference to a bed is to be understood as applying alsoto any other kind of support. For example, the data indicative of thekind of image to be taken (e.g., data indicative of the region ofinterest) may dictate a certain relation between the patient (or patientsupport) and the gantry. The data indicative of the kind of image to betaken and the corresponding relation between the patient or patientsupport and the gantry may be provided in the form of a lookup table.

In some embodiments, the determination is not of the arrangement of thedetectors directly, but of some other one or more parameters that affectthe detectors arrangement. For example, in some embodiments, such one ormore parameters may include the position of the patient support (e.g., aposition of a bed, on which the patient lies), in respect to the gantry.In another example, the parameters affecting the detectors' arrangementmay include a rotation angle of the gantry.

In some embodiments, bringing a detector to the vicinity of the patientis by extending an arm on which a detection head comprising the detectoris mounted. In some such embodiments, the detector may be made tocontrollably swivel in respect to the extendable arm on which thedetection head is mounted. The swivel may allow changing an aim angle ofthe detector, e.g., without changing a gantry angle. In someembodiments, each detector may swivel independently of the otherdetectors. In swivel-enabled embodiments, the one or more parametersaffecting the arrangement of the detectors may include the swivel angleof each detector in respect to the respective extendable arm.

In some embodiments, more than one arrangement of the detectors isdetermined for a single imaging process. For example, the imaging mayinclude collecting photons with the gantry at a first gantry angle, andthen collecting photons with the gantry at a second gantry angle. Insome embodiments, each gantry angle may be associated with a time periodfor collecting photons. In some embodiments, the gantry may revolvesmoothly along some angular range. In some embodiments, the one or moreparameters determining the arrangement of the detectors include theangular range and/or one or more paces of going along the angular range.

Alternatively or additionally, the imaging may include collectingphotons with the detectors at a plurality of different swivel angles. Insome embodiments, the swivel angles may be controlled, e.g., using arotary actuator; and the one or more parameters determining thedetectors' arrangement may include the swivel angles and/or the timedurations along which photons are collected at each swivel angle. Insome embodiments, the detector may swivel smoothly along a range ofswivel angles. In some embodiments, the one or more parametersdetermining the detectors' arrangement may include the range of swivelangles and/or the pace of going along said range. In some embodiments,each detector may be associated with a swivel angle monitor, forexample, a magnetic encoder. This way, the actual angle at which thedetector is aimed may be controlled, and not only the movementinstructions provided to the detector.

As mentioned above, each of said parameters that may affect thedetectors' arrangement in respect to the region to be imaged may bedetermined automatically based on two inputs: (1) what region is to beimaged; and (2) a model of the outer surface of the patient and bed (orother patient support). The model of the outer surface of the patientand bed may be generated based on input from one or more 3D sensors. Theone or more 3D sensors may provide coordinates of at least one point ofthe outer surface of the patient and/or bed, and these coordinates maybe used to model the outer surface.

Thus, an aspect of some embodiments of the invention includes a systemfor performing medical imaging of a region of interest in a patient. Thesystem may determine a desired position of the patient in respect to agantry. In some embodiments, the determination may be carried outautomatically, that is, the user may instruct the system to determinethe position, and the system carries out the determination withoutrequiring any further input from the user. As used herein, the termgantry refers to a frame, which provides mechanical support for mountingthe detector heads, such that the detectors can be positioned to scan apatient, or a part of the patient. In some embodiments, the gantry iscylindrical, and may be rotatable. In some embodiments of the invention,determining a desired position for the patient in respect to the gantryis carried out by the system, in some cases, without requiring thetechnologist attention. For example, the patient lies on a bed, adesired position for the bed is determined by the system, and the bed ismoved to this desired position, in some embodiments, after atechnologist confirmed such movement. In some embodiments, the patientsupport is static and the gantry moves to achieve the determinedrelative positioning between the patient support and the gantry. In someembodiments, the gantry is stationary and the patient support is moved.In some embodiments, both of patient support and gantry are moved inorder to achieve the determined relative position.

In some embodiments, the imaging takes place with the patient lying on abed, couch, or any other support. In some such embodiments, the systemmay determine a vertical positioning of the support. For example, if thecouch is at a center of a gantry of the system, higher than the center,lower than the center, and by how far. Alternatively, or additionally,the system may determine a horizontal positioning of the support. Forexample, the system may determine where the gantry should be along alongitudinal axis of the patient.

In some embodiments, the imaging takes place with the patient sitting.For example, when imaging a leg, the patient may sit and the leg may beoutstretched and supported by the patient support. In some embodiments,the imaging takes place with the patient in standing position, forexample, for imaging under loading stress. The patient support may thenhave a form of a supporting wall and/or floor. In some embodiments, thebody support may be a support for a breast. The body support may also beof any other kind or form.

In some embodiments, the system may include a computer programmed todetermine the desired position of the support in respect to the gantry.To determine the desired positioning of the support, so that the patienthimself is well positioned, it is useful to have information on theouter surface of the patient, and in some cases also of the support.Accordingly, in some embodiments of the present invention, thepositioning (vertical and/or horizontal) is determined based oninformation regarding the outer surface of the patient and support. Theinformation may include coordinates of one or more points on the outersurface of the patient (referred to herein as “surface points”). Thecomputer may be programmed to estimate from the surface points a 3Dstructure of the outer surface of the patient (and support), and this 3Dstructure may provide basis for determining the desired position of thesupport. In some embodiments, the desired position may be determineddirectly from the coordinates of the surface points, without generatinga model of the outer surface. The outer surface is also referred toherein as “contour”, and the terms are used herein interchangeably.

The coordinates of the surface points may be received from one or more3D sensors. Each of the 3D sensors can be any device that providesinformation of the spatial location of at least one point belonging tothe outer surface of the patient and/or support. In embodiments of thepresent invention, the information is provided at well-defined physicalunits (e.g., cm or inches). The computer may be programmed to determinethe desired positioning of the support in respect to the gantry based onthe coordinates of the one or more surface points. In some embodiments,the computer may be programmed to estimate, based on the coordinates ofthe surface points, a 3D structure of the outer surface of the patientand support, and use this estimated structure to determine the desiredpositioning of the support in respect to the gantry.

For example, in some embodiments, there may be a desire to localize thecenter of the patient at the center of the gantry. This may be the case,for example, when an entire torso of the patient is to be scanned. Insome such embodiments, the vertical positioning of the bed may depend onhow large the patient is. With large patients, the front side of thebody will be further from the support than with skinny patients. Whileone may not need an automatic measurement system to tell large fromskinny, more delicate distinctions may be made by the system, allowingaccurate positioning that in absence of information from the 3Dsensor(s) may require several minutes of trial and error. For examples,in some embodiments, the determined position of the patient supportbrings the center of the patient to the center of the gantry (or to anyother position in respect to the gantry) in accuracy of millimeters,e.g., 5, 2, 1, or 0.5 millimeter. Obtaining such accuracy with thesystem disclosed herein may save several minutes that would be requiredfor positioning the patient using available means, even by the mostexperienced user. These minutes, saved with each patient, may allow morepatients to benefit from imaging by the same device during a given timeperiod.

In operation, according to some embodiments of the invention, beforescanning begins, the patient lies on a bed, and the technologist entersto the computer an indication to a type of scan to be carried out. Thisindication may be provided by a user interface, which may include, forexample, a touchscreen, a keyboard, and/or a barcode reader. In someembodiments, the type of scan may be retrieved from a databaseassociating scan types with patients' identifiers. For example, thephysician may enter into the personal file of the patient a scan requestindicating the scan type. By scanning a barcode encoding a patientidentifier (e.g., an ID or national insurance number of the patient),the kind of scan may be retrieved from the database. The technologistmay, in some such cases, only verify that the patient he is dealing withis indeed the patient whose name is associated with the identifier.

The type of scan (also referred to herein as a scan type, scan kind, orkind of scan) may indicate, for example, the region of interest (e.g.,liver, brain, a certain brain section, etc.), a scan category (e.g.,planar, 3D, preview, etc.), the required quality (e.g., diagnostic ornon-diagnostic), or a combination of any of these. The technologist maymove the couch with the patient lying on it, so that the detector isroughly at the region to be imaged. Then, the user may send a controlsignal to the 3D sensor(s) to sense the outer surface of the patientand/or bed, and send coordinates of at least one surface point to thecomputer. The control signal may be sent by the user via the userinterface. In some embodiments, a “start scanning” button may cause acontrol signal to be sent to the at least one 3D sensor. The at leastone 3D sensor may be activated, at this or at any other stage of theimaging process, by the processor, without necessitating an explicitcontrol signal to be initiated by the technologist.

The computer may determine the desired positioning of the patient'ssupport based on the information received from the 3D sensors. Forexample, the computer may have a default instruction to bring the centerof the patient to some predetermined location (e.g., the center of thegantry). The computer may determine the location of the center of thepatient based on the coordinates of the at least one surface point. Forexample, the computer may be preprogrammed to fit a curve thatapproximates the patient's outer surface base on the coordinates of theat least one surface point, and approximate the center of the patientwith a center of an area (or volume) defined by the fit curve.

In some embodiments, the scan type may also be used for determining atarget for the relative positioning of the patient support and thegantry. This target may be referred to herein as a desired positioning.For example, the computer may be preprogrammed to bring the outersurface of the patient to the center of the gantry for scans of certaintypes (e.g., for planar scans), and bring the center of the patient tothe center of the gantry at other scan types. It is to be noted thatusually, information on the current position of the patient support isalso available for the computer for determining the target positioning.

Once a desired positioning is determined, e.g., as described above, thecomputer may indicate this determination to the technologist. Suchindication may be, for example, by displaying on a display a distancethe patient support is to be moved (e.g., up or down), and/or an imagesymbolizing the patient supported by the support in the determinedposition, optionally in the environment of the gantry. The technologistconfirms bringing the support with the patient thereon to the determinedposition, and a motor moves the bed to the position determined. In someembodiments, the confirmation is in response to an indication providedto the user by the system regarding the determined position. In someembodiments, the confirmation is given in advance, e.g., as a default.In some embodiments, the system automatically positions the patientsupport, without the need for operator confirmation.

In some embodiments, the user may indicate a body part desired to bescanned on the user interface, for example by selecting from apredefined list of body parts, or by selecting scan limits on a humanavatar. In some embodiments, the body part desired to be scanned may beread from the patient file as mentioned above (e.g., after identifyingthe patient by reading a respective barcode). The system may then useinput from the 3D sensors to get a model or point cloud of the patient,and analyze it to find the location of the body part to be imaged on the3D model/point cloud. The processor may then position the bed at thedesired location, in some embodiments, horizontal location, e.g., inresponse to a technologist confirmation.

DETAILED DESCRIPTION OF THE DRAWINGS

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details of construction and the arrangement of thecomponents and/or methods set forth in the following description and/orillustrated in the drawings and/or the Examples. The invention iscapable of other embodiments or of being practiced or carried out invarious ways.

FIG. 1A is a flowchart of a method 1000 of scanning at least a portionof a patient with a scanning apparatus comprising a gamma detectoraccording to some embodiments of the invention. The gamma detector maybe mounted on an arm extending towards the patient. FIG. 18 shows aportion of the patient (1025), a gamma detector (1035), a sensor (1045),and some points and directions mentioned in the description of method1000. More detailed descriptions of gamma detectors are provided in FIG.6A and FIG. 6B.

At 1010, data indicative of coordinates of points (e.g., 1015, 1017,1019)) on the outer surface of the patient (1025) are obtained. The dataindicative of the coordinates may be received from at least one 3Dsensor (1045), and may include, for example, the coordinates themselves,in some coordinate system. In some embodiments, the coordinates may beprovided in a coordinate system of the scanning apparatus. In someembodiments, the coordinates may be provided in a coordinate system ofthe detector (1035), the sensor (1045) or any other coordinate systemthat may be transformed to that of the scanning apparatus. In suchembodiments, the data may be transformed to a coordinate system of thescanning apparatus, or any other coordinate system, allowingrepresentation of the outer surface of the patient and the gammadetector on a common coordinate system.

In some embodiments, the data indicative of the coordinates of surfacepoints of the patient may include data indicative of the coordinates ina less direct manner. For example, the data may include a distance D1from the patient to the gamma detector along a specified direction. Suchdistance may allow computing the coordinates of a surface point based onthe distance, the direction, and the coordinates of the gamma detector.Similarly, the data may include a distance D2 from the patient to a 3Dsensor (1045) along a specified direction. Such distance may allowcomputing the coordinates of a surface point based on the distance, thedirection, and the coordinates of the 3D sensor.

In another example, the data may be directly indicative to thecoordinates of some points, and indirectly indicative to coordinates ofsome other points. For example, the data may include coordinates of somesurface points (e.g., 1015, 1017). These surface points may be used forestimating coordinates of other surface points (e.g., 1019). Theestimation may be based on an approximation, for example, interpolation,extrapolation, triangulation, and others. Under such circumstances, thedata may be considered indicative of the coordinates of the othersurface points estimated by approximation (e.g., 1019) as well as beingindicative of coordinates of point(s) directly indicated (e.g., 1015,1017).

In some embodiments, the gamma detector may be mounted on an arm (1055)extendible towards the patient. The extension direction of the arm maybe the above-mentioned specified direction, for example, the dataobtained in 1010 may be indicative of a distance between the gammadetector and a point on the outer surface of the patient along extensiondirection D1 of arm 1055. Data indicative of that distance may include,for example, the distance itself, other distances, that allow estimatingan approximation to that distance, coordinates that allow calculationand/or estimation of that distance, etc.

At 1020, a target position is determined for the gamma detector. Thetarget position may be determined based on the data obtained at 2010.For example, the obtained data may be indicative of the distance D1between gamma detector 1035 and the patient along the extensiondirection of arm 1055. In some embodiments, the distance along thatdirection should be as small as possible without touching the patient.Thus, if data obtained at 2010 is indicative to that distance D1 is, forexample, 25 cm, the target position determined at 1020 may be closer tothe patient by 24.5 cm along the same line. If, however, the dataobtained in 1010 indicates that at similar directions (e.g., directionsthat deviate from the extension direction of arm 1055 by an angle αsmaller than a predetermined angle), the outer surface of the patient iscloser to the gamma detector than at the extension direction of arm1055, then the position may be determined to be further away from thepatient (e.g., P1), so no point of the outer surface of the patient istouched. The avoided touch may be between the patient and the detector,or between the patient and a detection head comprising the detector, asdescribed herein.

In some embodiments, the data obtained in 2010 is indicative to thedistances of several points along the gamma detector from the patient.The distances may be along directions parallel to the extensiondirection of the arm, and the target position may be determined so thatthere is no contact between the patient and the detector at any of thesepoints.

In some embodiments, a plurality of target positions may be determinedat 1020 to a single gamma detector based on the data obtained at 1010.For example, the data obtained at 1010 may be used to determine a numberof angular positions, at which the detector is to be detecting gammaradiation from the patient, for example, as described in FIG. 6A or FIG.6B below. In another example, the data may be used to determine aplurality of swivel angles or a range of swivel angles, as describedherein.

At 1030, the gamma detector (1035) is caused to detect gamma radiationfrom the patient when the gamma detector is at the target position. Ifmore than one target position has been determined in 1020, the gammadetector may be caused to detect gamma radiation when it is in one ormore of them. Causing the gamma detector to detect gamma radiation mayinclude, for example, sending to the gamma detector a control signal,for example, from processor 108 discussed below. In some embodiments,the gamma detector may be controlled to move to the target position, anddetect gamma radiation when it is at the target position. In someembodiments, the target position is characterized by the distance,position, and/or orientation of the detector in respect to the patient,or the portion of the patient that has to be imaged. The patient (or atleast the portion to be imaged) may be moved in respect to the detectorin addition to moving the detector, or instead of moving the detector.The patient or portion to be imaged thereof may be moved, in someembodiments, by moving a support supporting the patient or said portionthereof.

The movement of the detector may include extending the arm to get closerto the patient. In some embodiments, the movement may include changing adirection along which the arm is extended. For example, when the arm issupported on a gantry, the movement may include rotation of the gantry.The gamma detector may be controlled to settle at the target position,so that gamma radiation is detected when the detector is stable at itsposition. In some embodiments, a range of target positions may bedetermined, and the gamma detector may be controlled to move fluentlyalong that range and detect the radiation during the movement. Forexample, when the target positions are arranged at different angles inrespect to the patient (e.g., at different gantry angles), the detectormay be moved around the patient (e.g., by rotating the gantry), anddetect gamma radiation during this movement. In another example, whenthe target positions include a plurality of swivel angles, the detectormay be controlled to swivel and detect gamma radiation during theswiveling. In some embodiments, swiveling and gantry rotation may besimultaneous.

In some embodiments, after a first target position is determined basedon a first set of data (e.g., as in 1010 and 1020), the detector ismoved to the first target position, and then data is obtained onceagain, and a second target position is determined. In some embodiments,no gamma radiation is detected when the gamma detector is at the firsttarget position. Then, the detector may be moved to the second targetposition, and gamma radiation may be detected with the gamma detector atthe second target radiation. In one example, such a process may becarried out when the first target position is characterized by a certainangular positioning of the arm (e.g., a gantry angle). When the detectoris at the determined angular position, another set of 3D data may beobtained, for example, to determine a target position of the detectoralong the extension direction of the arm (which has changed in view ofthe first set of data obtained). Then, the gamma detector may be movedalong that direction, e.g., by extending the arm to proper proximity tothe patient.

In some embodiments, the scanning is carried out using two or more gammadetectors. The two or more gamma detectors may be operated to detectgamma radiation simultaneously (that is, at overlapping time periods),to save scanning time. Each of the gamma detectors may be mounted on anarm of its own, and its arm may extend towards the patient along arespective direction. In some such embodiments, the scanning method mayinclude obtaining data indicative of a distance from the patient alongthe respective specified direction for each of the gamma detectors.Based on data indicative of at least some of these distances, arespective target position may be determined for each of the gammadetectors. Then, the gamma detectors may each be caused to detect gammaradiation from the patient at the respective target position.

In such embodiments, the interactions between the various detectorsand/or arms are taken into consideration. For example, in someembodiments, each gamma detector is in a respective detection head, andthe target position of each gamma detector is determined inconsideration of target positions of other gamma detectors to ensurethat the detection heads do not collide or otherwise interfere with eachother.

In some embodiments, the method may include, in addition to receivinginformation as discussed in relation to 1010, receiving data indicativeof the kind of image to be taken. Some such embodiments are discussed inmore detail below.

FIG. 1C is a diagrammatic illustration of a system for performingmedical imaging of a region of interest according to some embodiments ofthe invention. System 100 includes a support (102), a gantry (104), atleast one 3D sensor 106, (4 3D sensors are shown) and a processor (108).

Support 102 is configured to support patient 110 during imaging. Thepatient support may be configured to support lying patients, asillustrated. In some embodiments, the patient support may be configuredto support standing patients, sitting patients, and/or leaning patients.For example, the support may be horizontal, such as a patient bed,vertical, such as a wall or a back of a chair and the like. The supportmay be made of low attenuation material, for refraining from attenuatinggamma radiation emanating from the patient towards the detectors on theother side of the support.

Gantry 104 includes a cylindrical frame that supports multiple detectionheads 112. In some embodiments, in each detection head, the gammadetector faces support 102. An example of a detection head is describedbelow in relation to FIG. 6A and FIG. 6B. Each detection head 112 may bemounted on an extendable arm 116, configured to take the detection headmounted on it in a linear in-out movement, so as to bring the detectorcloser to the patient or away of it. Gantry 104 is rotatable around anaxis, along, for example, angle ϕ, to allow the gamma detectors torotate around the support.

Each detection head 112 may include one or more gamma detectors, such assemiconductor radiation detectors, for example nuclear medicine (NM)detectors, for instance cadmium zinc telluride (CZT) detectors. A linearactuator is provided to linearly maneuver extendable arm 116 so thatdetection head 112 moves toward and from patient support 102 (alsoreferred to herein as support 102). Optionally, the linear actuator ismechanical actuator that converts rotary motion of a control knob intolinear displacement, a hydraulic actuator or hydraulic cylinder, forexample a hollow cylinder having a piston, a piezoelectric actuatorhaving a voltage dependent expandable unit, and/or an electro-mechanicalactuator that is based on an electric motor, such a stepper motor andthe like. In some embodiments, the linear actuator may include a steppermotor and a sensor, optionally a magnetic sensor (e.g., encoder) thatsenses the actual position of detection head 112, to provide feedback onthe control of the stepper motor. The control of each linear actuatormay be performed according to a scanning plan. In some embodiments, thescanning plan may be generated by processor 108.

Sensor 106 is a 3D sensor arranged to sense a portion of patient 110when the patient is supported by support 102. Sensor 106 may be, forexample, optical, ultrasonic, or based on radio waves or microwaves.Examples of specific technologies used in such sensors are structuredlight sensors, illumination assisted stereo sensors, passive stereosensors, radar sensors, Lidar sensors, and time of flight sensors.Commercially available embodiments of such sensors include MicrosoftKinect, Intel® RealSense™ Camera F200, Mantis Vision's 3D scanners, PMDtechnologies PicoFlexx, and Vayyar imaging Wallabot. Sensor 106 isconfigured to output signals indicative of 3D coordinates of points(e.g., point 114, 114′) on an outer surface of patient 110 and/orsupport 102. In some embodiments, the 3D sensor(s) provides a pointcloud that allows approximating the outer surface of the bed and/orpatient. In some embodiments, the 3D sensor may be installed on thegantry, as shown in FIG. 1 . Alternatively or additionally, one or more3D sensors may be installed on the extendable arm 116, inside detectionhead 112, on a separate support structure, or at any other location, atwhich the one or more 3D sensors can sense the position of at least onepoint of the outer surface of the patient and/or support.

Processor 108 may be configured to determine a desired position ofsupport 102 in respect to gantry 104 based on data obtained by 3Dsensors 106. As used herein, if a machine (e.g., a processor) isdescribed as “configured to” perform a particular task (e.g., determinea desired position), then the machine includes components, parts, oraspects (e.g., software) that enable the machine to perform theparticular task. In some embodiments, the machine may perform this taskduring operation. Processor 108 is diagrammatically described in FIG. 2. Processor 108 may include an input 202 configured to receive from 3Dsensor 106 data indicative of at least one surface point 114. The datareceived from the processor may be raw data, convertible to 3Dcoordinates of the one or more surface points by processor 108 or anyprocessing module connected to processor 108. In some embodiments, the3D sensors may send the coordinates directly to processor 108. Dataindicative of the 3D coordinates of the one or more surface points maybe stored in memory 204. In some embodiments, memory 204 may store onlythe most update data received from sensors 106. In some embodiments,memory 204 may store the data for longer term, so as to allow furtheranalysis of the data after imaging is concluded. This may help, forexample, to correct for patient motion, and/or to identify in retrospectcertain images of the outer surface of the patient as being taken at acertain point along a respiratory phase, for example, during exhale orinhale. Processor 108 may further include a memory 206 storinginstructions for determining a desired position of the support inrespect to the gantry based on the data received by the input. Memory206 may be separate from memory 204, or may make part of memory 204. Anexample of a method by which processor 108 may determine the desiredposition is described in FIG. 3C. Processor 108 may further include acentral processing unit (CPU) 208 configured to carry out theinstructions saved on memory 206 using data stored on memory 204 andsend results of the processing to output 210.

Output 210 may be connected to display 212. Display 212 may be, forexample, a visual, audial, or visual-audial display. Display 212 may beconfigured to indicate to a user the desired position of the support inrespect to the gantry, as determined by processor 108, based on inputreceived at the display from output 210. In some embodiments, output 210may be connected to a motor (not shown) configured to move support 102to the determined position. The connection to the motor may be inaddition to the connection to the display.

System 100 may also include a user interface 214. User interface 214 mayallow the user (for example, a technologist) to indicate a kind of scanto be performed. The user interface may include, for example, a barcodereader to read a barcode attached to an imaging request for the patient.Optionally or alternatively, the user interface may include a keyboard,touchscreen, or any other input device allowing the user to indicate thekind of scan required. In some embodiments, details of the required scanmay be inputted from another computer, e.g., through an intranet orthrough the Internet. Such input may be in addition to, or instead of,input from user interface 214. User interface 214 may also include atleast one control for sending a control signal to the 3D sensor(s) tosense the outer surface of the patient and bed. In some embodiments,user interface 214 may also allow the user to confirm that the positiondetermined by processor 108 is acceptable, and if such confirmation isreceived, the processor may control a motor to position the patientsupport according to the determination. In some embodiments, the displayshows instructions for moving the patient support, and the user operatesthe motor manually according to the instructions. In some embodiments,after positioning (manual or automatic), the user may control the 3Dsensor to sense the patient and bed once again, to verify that theposition of the bed indeed brings the patient to the required positionin respect of the gantry, and if not (e.g., because the patient moved),the process of determining and moving the bed may repeat until thepositioning is satisfactory.

In some embodiments, processor 108 may be configured to have differentor additional functions. For example, processor 108 may be configured(e.g., by proper programming) to generate a scanning plan. The scanningplan may be for imaging of at least a portion of a patient. In someembodiments, processor 108 may be configured to receive informationindicative of the location of at least one point sensed by 3D sensor(s)106, and generate the scanning plan based on the received information.In some embodiments, the processor may be further configured to receiveinformation indicative of the type of scan, e.g, of the region to bescanned, and generate the scanning plan based on the type of scan andthe location of the at least one point. The information indicative ofthe region to be imaged may be received by processor 108 from a userthrough user interface 214. In some embodiments, scanning plan may begenerated based on a kind of scan. Kinds of scan are described herein.The terms type of scan, kind of scan, type of image, and kind of image,as well as image kind, image type, scan kind and scan type are usedherein interchangeably.

The scanning plan may include, for example, a number of gantry positionsand corresponding gantry angles. In some embodiments, the scanning planmay include a dwell time for each gantry position. In some embodiments,all the dwell times are planned to be of equal length. In someembodiments, two or more of the dwell times may differ from each other.Additionally to parameters pertaining to the gantry positions, oralternatively to such parameters, a scanning plan may include aplurality of swivel angles, for one or more of the detectors. In someembodiments, the plan may associate each of the swivel angles with acorresponding dwelling time. The dwelling times may be all equal, orthey may include two or more dwelling times that differ from each other.Some considerations for determining gantry angles, swivel angles, andcorresponding dwelling times are described herein.

In some embodiments, the scanning plan may include parameters forcontinuous scanning. For example, a first and second gantry positionsand a rate of continuously advancing the gantry between said first andsecond gantry positions. In some embodiments, the rate of advancing thegantry between the first and second positions (or a plurality of rateseach for a portion of the path between the two positions) may also beincluded in the scanning plan.

In some embodiments, the scanning plan may include a positioning of thesupport in respect of the gantry.

FIG. 3A is a flowchart of a method (350) of imaging a region of interestin a patient. The imaging may be by a medical imaging device comprisinga plurality of gamma detectors supported on a gantry. The gantry mayface a support for supporting the patient, or a portion of the patient,during imaging. The portion of the patient supported by the support mayinclude the region of interest.

At 352, an indication of the kind of image to be taken is received. Thekind of image may include, for example, the region of interest (e.g.,brain or liver), the kind of scan (e.g., planar, 3D, preview, or dynamicplanar preview), the required quality (e.g., diagnostic ornon-diagnostic), or a combination of any of these.

At 354, coordinates of at least one point of an outer surface of thepatient and/or support are received. The coordinates may be in thecoordinate system of the medical imaging device. In some embodiments,the coordinates may be in physical units, for example, centimeters orinches.

At 356, at least one parameter affecting an arrangement of the gammadetectors in respect to the region of interest is determined based onthe indication of the kind of image and the coordinates of the at leastone point. The at least one parameter may include, for example, aposition of the support in respect to the gantry, one or more gantryangles, and/or a range of gantry angles.

In some embodiments, each of the gamma detectors is mounted on an armextendable from the gantry towards the support. The mounting may allowthe gamma detector to swivel in respect to the arm. In such embodiments,the at least one parameter affecting the arrangement of the gammadetectors may include swivel angle of at least one of the detectors. Theswivel angle may be determined in respect to the arm on which therespective detector is mounted. In some embodiments, the at least oneparameter may include a plurality of swivel angles for one of thedetectors, for some of the detectors, or for each of the detectors. Insome embodiments, the at least one parameter may include a range ofswivel angles. For example, each detector may have its own range ofswivel angles, or some detectors may have a range of swivel angles andsome only a single swivel angle, etc. In some embodiments, the rangesmay differ from one another.

In some embodiments, the one or more parameters affecting thearrangement of the detectors may include a dwelling time for one or moreof the positions. For example, a dwelling time for each gantry position,a dwelling time for each swivel angle, etc. may be determined for one ormore of those parameters. The determination of the dwelling time mayalso be, in some embodiments, based on the coordinates of the point(s)of the outer surface of the support and/or patient. For examples, thecoordinates may be used to spatially model the patient, and the dwellingtimes may be determined so that, in accordance with the model, longerdwelling times are associated with detector positions at which gammaradiation is collected from a thicker portion of the patient. In someembodiments, the dwelling times may be determined based on the scan typein addition to the coordinates of the surface points. For example, ifthe kind of image indicates a region of special interest (e.g., thepancreas), the location of the region of special interest may beestimated based on a model of the outer surface of the patient, anddwelling times for positions facing the region of special interest maybe longer than dwelling times for positions facing other portions of thepatient. For example, in some embodiments, a dwelling time may bedetermined for each gantry angle, and/or for each swivel angle of eachdetector. Similarly, in case the one or more parameters include a rangeof gantry angles, a pace by which the gantry is to be moved along therange may also be determined at 356. Similarly, in case the one or moreparameters include a range of swivel angles for a detector, a pace bywhich the detector is to be moved along the range of swivel angles mayalso be determined at 356. The swivel pace may be determined similarlyto dwelling times, with slow pace being determined under circumstancessimilar to those to which longer dwelling times are determined.

At 358, the gamma detectors, the gantry, and/or the support arecontrolled in accordance with the at least one parameter determined. Forexample, in some embodiments, processor 108 may send control signals toa motor that moves support 102 until the support is positioned at theposition determined at 356. In another example, processor 108 may sendcontrol signals to a linear actuator that extends one of arms 116.Processor 108 may receive signals from a sensor that senses the positionof the detector mounted on the arm 116, and keep sending control signalsto the actuator until the signal received from the sensor indicates thatthe detector is at the position determined for it at 356. Similarly,processor 108 may send control signals to motors moving the gantry,and/or to motors that swivel each of the respective detectors, andverifies that the movement is in accordance with what's determined at356.

FIG. 3B is a flowchart of a method 370 similar to method 350 describedabove, but method 370 includes (at 372) generating a model of the outersurface of the patient and/or the support. The model may be generatedbased on the coordinates of the at least one point received at 354. Insome embodiments, the model generated at 376 may be a 3D model of theouter surface of the patient and the bed. The term model may encompassany estimate of the structure of the outer surface of the patient and/orthe bed. For example, in some embodiments, a general shape of the outersurface may be presumed (e.g., stored on a memory accessible toprocessor 108), and the exact dimensions of this general shape may befit to the coordinates of the surface points, as these are received at354. For example, the general shape may be provided as a parametricformula of a curve, and the values of the parameters may be found fromthe points by interpolation or by best fit methods.

In some embodiments, for example, when a rich point cloud is receivedfrom the 3D sensors, the model of the outer surface may be generatedwithout presuming a general shape, but only by processing (e.g., byinterpolation) the provided coordinates. In some embodiments, someknowledge of the shape (e.g., knowledge of the shape of the bed) may beused to help in generating the model.

In method 370, 356 may be replaced by 376, at which the at least oneparameter that affects the arrangement of the detectors in respect tothe region of interest is determined based on a location of the regionof interest in respect to the model generated at 372. For example, whenthe region of interest is viewed in the context of the outer surface ofthe patient and bed, the outer surface may pose boundary conditions onthe positioning of the detectors, and the shape of the region to beimaged may pose minimal requirements of coverage by the detectors.

FIG. 3C is a flowchart of a method (300) of determining a desiredvertical position of the patient support according to some embodimentsof the invention.

At 302 a kind of scan is received, e.g., from user interface 214.

At 304 a position of the patient in respect of the gantry is determinedbased on the kind of scan. For example, in some embodiments, memory 206may store a lookup table connecting each kind of scan with a desiredposition of the patient in respect of the gantry. In such a lookuptable, some scan types may be associated with positioning the center ofthe patient at the center of the gantry. Some scan types (e.g., frontalplanar scan) may be associated with positioning the frontal surface ofthe patient at the center of the gantry, or at any other predeterminedposition in respect to the gantry, for example, the position that allowsmaximal coverage of the front of the patient with detectors.

At 306 data from sensor(s) 106 is received.

At 308 the data received from the sensors is used to determine theposition of the bed, at which the patient is at the required position inrespect to the gantry. For example, if the kind of scan indicated viathe user interface is associated with a target of bringing the center ofthe patient to the center of the gantry, the data received from the 3Dsensor(s) is analyzed to find the center of the patient. If the kind ofscan is associated with a target of bringing the front of the patient towhere detectors can reach the front surface as close as possible withoutinterfering with each other and without the patient or patient supporthitting the gantry, the data from the 3D sensor(s) may be used fordetermining the position of the bed, at which this condition isachieved.

In some embodiments, the data received from the one or more 3D sensors106 is used to generate a 3D model of the outer surface of the patientand the bed, or otherwise estimate the structure of the outer surface ofthe patient and the bed. For example, a general shape of the outersurface may be presumed, and the exact dimensions of this general shapemay be fit to the coordinates of the surface points, as these arereceived from the 3D sensors. For example, the general shape may beprovided as a parametric formula of a surface, and the values of theparameters may be found from the points by interpolation or by best fitmethods.

In some embodiments, for example, when a rich point cloud is receivedfrom the 3D sensors, an approximation to the outer surface may begenerated without presuming a general shape, but only by processing theprovided points. The processing may include, for example, filtering thedata, cleaning from outliers or other noisy data, and interpolating ortriangulating the filtered/cleaned data. In some embodiments, someknowledge of the shape (e.g., knowledge of the shape of the bed) may beused to help in generating the approximation. In some embodiments, theapproximation to the outer surface of the patient and/or supportgenerated based on the coordinates of at least one surface point, may beused for determination of the at least one parameter that affects thearrangement of the detectors in respect to the region of interest.

The determination may be based on a location of the region of interestin respect to the model. For example, the model may set limitation onwhere the detectors may be positioned when determining positioning ofthe bed, gantry positions, swivel angles, etc. For example, the modelmay limit the detectors or the detector heads to be out of the outersurface, at some minimal distance from the face of a patient, etc.

In some embodiments, a quick, non-diagnostic, nuclear image may be takenby the gamma detectors, and based on that the positioning of the patientmay be evaluated, to see if the current positioning is adequate or not.This may be useful particularly for the horizontal positioning along thelongitudinal axis of the patient. If the imaging shows that some of theregion of interest is outside the image, positioning is adjusted tocorrect for this.

FIG. 4 is a diagrammatic illustration of a system according to someembodiments of the invention with a center (c) of a patient 110 at thecenter of gantry 104. The position of the center of the patient may havebeen determined by processor 108 based on data from 3D sensors 106. Ascan be seen in the drawing, all the detectors are as close as possibleto the patient. This configuration may be suitable, for example, forimaging a region at the center of the patient (e.g., liver), for ageneral scan not particularly focused at any region inside the patient'sbody portion surrounded by the detectors, and in many others. As may beappreciated, although there are as many as 6 detectors that make goodcontact with the patient's body, the distances between them are quitelarge, and to obtain photons from the entire imaged region at allpossible directions there may be a need to rotate gantry 104, so thatdata is collected at one or more additional gantry rotation angle(s). Inthe presently illustrated case, as there are 12 detectors, spaced fromeach other equally around the gantry, the angular difference betweeneach two adjacent detectors is 30 degrees, and the additional gantryangle may be set 15 degrees from the present gantry angle.

FIG. 5 is a diagrammatic illustration of the system and patient depictedin FIG. 4 , however, in FIG. 5 the kind of image may be a frontal planarimage, or any other image kind that would benefit from detectors thatcover most closely the front part of the patient. In such a case, bed102 may be lowered in gantry 104 so the extendable arms mounting thedetectors that face the front side of the patient may be extended longerinto the gantry than in FIG. 4 , and cover the front side of the patientmore densely than in FIG. 4 . This way, collecting gamma photons from asingle gantry angle may be enough in order to obtain a good imaging ofthe front of the patient. On the other hand, the contact between some ofthe detectors and the patient may be poorer than in FIG. 4 . See, forinstance, detectors A and B.

FIG. 6A is a cross-sectional illustration of a detection head 112according to some embodiments of the invention. Detection head 112 has abreadth B, length L and height H (see FIG. 6B for the length L andheight H). Detection head 112 may include a detecting unit 602 in ahousing 604. For example, the detector units 602 may be housed toprotect patient 110 from swivel motion (illustrated by the arrow 620) ofthe detecting unit 602. Housing 604 may have a round or curved cover. Insome embodiments, housing 604 includes a cover shaped with a section 608of a cylinder that allows for the swivel of the detecting unit 602around a swiveling axis 610. Detection head 112 is shown to include aparallel hole collimator 612. Such a collimator may be used to gaininformation about the direction from which each photon arrives at thedetection layer 614. Collimator 612 may include thin walls 616 (alsoreferred to as septa) that define channels parallel to each other. Thewalls may be made of materials that have high linear attenuationcoefficient for gamma radiation, such as lead or tungsten. Each photonmay be considered to arrive to a point where it hits detection layer 614through a channel of the collimator. Most of the photons that hit septa616 are absorbed by the septa, so that mainly photons that go nearlyperpendicularly to detection layer 614 reach the detection layer. Thenear perpendicularity may be expressed as a solid angle, from which thephotons have to emerge in order to have a high probability (e.g., largerthan 90%) to reach the detection layer. Detecting unit 602 may alsoinclude a heat sink (618), which may be attached to the detection layeron the detection layer side free of collimator 612. Detection head 112may also include electronics (not shown) for transferring data to andfrom the detection layer to processor 108.

While the explanations above refer to a collimator known in the field asa parallel hole collimator, one or more of collimators 612 may be of adifferent kind, for example, a pinhole collimator, a slant holecollimator, or a fan beam collimator (e.g., a converging collimator, ora diverging collimator). In some embodiments, different detectors 112may include collimators of different kinds.

Detection head 112 may include further parts, as well known in thefield. For example, the detection layer 614 may include a plurality ofdetection modules, and each may have its own ASIC (Application SpecificIntegrated Circuit). The detection head may further include a carrierboard which holds all of the detection modules, and interfaces to theASICs. The detection head may also include shielding from externalradiation, additional mechanics to hold the detection layer, ASICs,electronics, cover, etc., together. The detection head may also includea swivel motor, a swivel axis, belt, tensioners, encoder for encodingthe exact swivel angle, electronic boards to control the motion of thedetector (with the detection head and/or inside the detection head), andelectronic boards to transfer data indicative of the photons received atthe detection layer.

FIG. 6B is a cross-sectional illustration of the detection head shown inFIG. 6A along a cross-section perpendicular to that depicted in FIG. 6A.FIG. 6B illustrates that in some embodiments detection head 112 may beelongated, for example, to almost contact with the patient along a lineparallel to the longitudinal axis of the patient. The length of detector602 may be sufficient to allow acquiring the entire scan without movingthe patient (or the gantry) along the patient, and yet short enough toallow maximal proximity between the detector and the patient taking intoaccount body curvatures. A length of about 30 cm to 40 cm is found to besatisfactory for imaging grown up humans. FIG. 6B also shows extendablearm 116 (not shown in FIG. 6A). In some embodiments, the angle betweenextendable arm 116 and detector 602 is fixed, e.g., as 90°. In someembodiments, the angle between extendable arm 116 and detector 602 maybe controllable, e.g., by processor 108. In some embodiments, the lengthof detector 602 is about 30 cm, the length of the outer cover is about40 cm, and the radius of curvature of the round part 608 of cover 604 isabout 5 cm. The length of the cover may extend beyond the length of thedetector, for example, to allow accommodation of electronics, encoders,and/or proximity sensors, (all not shown).

FIG. 7A is a flowchart of a method 700 for determining gantry anglesaccording to some embodiments of the invention.

At 702, data indicative of the outer surface of the bed and patient inrespect to the gantry may be received. Alternatively or additionally,the data or part thereof may be calculated based on information on theposition of the bed (e.g., as determined in method 300) and informationindicative of the outer surface of the bed and patient received from the3D sensors.

At 704, a position is determined for each one of the detection headsbased on the outer surface of the bed and patient in respect to thegantry, and a gantry combination.

The angular position of each detection head is determined based on agantry angle. A set of gantry positions required to accomplish a certainscan may be referred to herein as a gantry combination. Method 700 maydetermine a gantry combination iteratively. For example, at a firstiteration, there may be a default gantry combination, for example, acombination made of a single gantry position at some angle referred toherein as 0 degrees. At subsequent executions of step 704 the gantrycombination may include more than one gantry position. In method 700 thenumber of gantry positions in a combination (N) increases by one at eachexecution of step 704. In other embodiments (not shown), severaldifferent combinations of the same number of gantry positions may betried. In some embodiments, the angular distance between adjacent gantrypositions composing a single gantry combination may be equal. Thus, whenthe angular distance between two adjacent detection heads is 45 degrees,the first combination will include the gantry at angle 0, the secondcombination will include the gantry at angles 0 and 22.5 degrees, thethird combination will include the gantry at angles 0, 15, and 30degrees, etc.

The radial position of each detector may be determined as that, in whicheach detector is as close as possible to the patient. Finding thesepositions may take into account interactions between different detectionheads, for example, such that at each time, each portion of the spacearound the patient can be occupied by no more than one detection head.In some embodiments, an approximation of the outer surface may begenerated (e.g., by fitting an analytical curve to the one or morepoints received from the 3D sensor), and the position of the detectionheads are determined so that each detection head is as close as possibleor tangent to the fit curve. In some cases, when one detection head mayhinder the movement of another detection head (e.g., when the patient isnot at the center of the gantry), the processor may determine at 704which detector is to be closer to the patient, and which is left furtherfrom the patient, or decide that both detectors are at similar,intermediate distance from the patient. For example, in FIG. 5 it wasdecided to take detector B as close as possible to the patient and leavedetector A further from the patient outer surface. In anotherembodiment, shown in FIG. 7B, a different choice is made. Here,detectors A and B are positioned both away of the patient, but atsimilar distances, while in FIG. 5 detection head B almost touches thepatient, and detection head A is much further.

At 706 a scanning region is determined for each of the detectors. Insome embodiments, a scanning region may be the region from which thedetector can collect photons while swiveling the detection unit throughall possible swivel angles.

At 708 it is checked if the entire region to be imaged is covered from asufficient number of directions to facilitate the required image qualityby a combination of the scanning regions of all the detectors in all thegantry angles composing the gantry combination. The sufficient number ofdirections may be, for example, directions spanning 180°. If so (708:Yes), no further gantry combination need to be assessed, the number N ofgantry positions to be practiced during the imaging is determined, andthe process ends. If portions of the region to be imaged are outside thecombined scanning regions of all the detectors at all the gantrypositions composing the gantry combination, (708: No), an additionalgantry combination is to be assessed. At 710 this additional gantrycomposition is determined, the number N is increased by 1, and themethod may continue to 704.

In some embodiments, the swivel angles at which each detector collectsphotons may be determined for a given combination of gantry positions.Finding these swivel angles may be determined by a standard optimizingprocedure under the adequate constrains. For example, in someembodiments, an equal time is devoted for photon collection at eachswivel angle, and the optimization procedure is run to find the swivelangles that allow spending a minimal amount of time at each of thegantry positions. In an alternative embodiment, the optimizationprocedure is run to find the swivel angles that allow imaging the entireregion to be imaged at minimal imaging time. In some embodiments, thenumber of swivel angles used at each of the detectors is set to beequal, and this setting is used as a constraint on the optimizationprocedure.

In the above discussion it is assumed that gantry angles and swivelangles are controlled discretely. However, in some embodiments, thegantry angles, the swivel angles, or both, may be controlled to changecontinuously and fluently. This may save imaging time that otherwisewould be spent stabilizing the system after each and every event atwhich the gantry or any of the detectors stop moving. Reconstructingimages from moving detectors is generally known in the art of SPECT.Finding the limits of gantry continuous rotation may be found, forexample, as described in method 700, but once the gantry composition isfound, the gantry angles change fluently between the first and lastgantry position included in the gantry composition. For example, if thegantry composition determined by method 700 includes the gantrypositioned at angles of 0, 10, and 20 degrees, the continuous movementmay be between 0 and 20 degrees. Swivel ranges may be determinedsimilarly, for example, by finding necessary swivel angles as describedabove, and then moving fluently along angular ranges defined between thetwo most distanced swivel angles defined for each detector. In someembodiments, when swivel angles are changed continuously, the swivelrate of each detector is determined so that all the detectors begin andend swiveling together, so a detector that swivels along a broader rangeswivels faster than a detector that swivels along a narrower range.

In some embodiments, each swivel angle is associated with dwelling time(also referred to as a dwell time), along which gamma photons arecollected with the detector at the respective swivel angle. In someembodiments, the dwell times may be all of equal length. In someembodiments, two or more of the dwell times may differ from each other.In some embodiments, the dwelling times may be determined so that when adetector looks at a thicker portion of the patient the dwelling time islonger than when the detector looks at a thinner portion of the patient.For example, looking at the two horizontally mounted detectors in FIG. 4, which almost touch the patient's shoulders. When the detectors areaimed as in the figure, they collect photons from an extremely thickportion of the patient's body, extending from one shoulder to the other.However, when theses detectors are swiveled a little down (e.g., to facethe edge of the bed), they collect photons from a very thin portion ofthe patient. Therefore, in some embodiments, the dwelling time at thelatter swivel angle is much shorter than the dwelling time at the formerone. Dwelling times may be determined based on data indicative ofcoordinates of at least one surface point by modeling the outer surfaceof the patient and support based on the data indicative of thecoordinates, and determining the dwelling times using the thickness ofdifferent portions of the model, so that if, according to the model, adetector faces at a first position a thicker portion of the patient thatat a second position, the dwelling time at the first position will belonger than the dwelling time at the second position.

In some embodiments, each gantry angle is associated with dwelling time,along which the gantry is static at the respective gantry angle. Thegantry-angle related dwelling times may all be the same, or may includetwo or more mutually different dwelling times. The dwelling time of thegantry angle may be determined based on the longest dwelling timeassociated with any of the detectors. A dwelling time associated with adetector may include a summation of the dwelling times associated withall the swivel angles of the detector.

FIG. 7C is a flowchart of a method 750 for determining gantry anglesaccording to some embodiments of the invention. In some embodiments,this may be a calculation of a lower bound on the number of gantrypositions, and may be used as a starting point in FIG. 7A instead ofnaively starting with 1 as described there.

At 752 a linear scanning width is defined to each detector. In someembodiments, the linear scanning width may equal the breadth B of thedetector (illustrated in FIG. 6A). In some embodiments, the linearscanning length is defined before scanning begins. For example, it maybe preprogrammed into processor 108.

At 751, the linear scanning width of all the detectors is summed. Incase all the detectors are associated with the same linear scanningwidth, this width is multiplied by the number of detectors.

At 756, the number of gantry positions is determined as the quotientobtained by dividing an approximation of a circumference of the patientand the patient support by the sum of linear scanning widths obtained at751, to obtain a number of gantry positions. If the number of gantrypositions so obtained is not a whole number, it may be rounded, forexample, to the nearest whole number.

The approximation of the circumference may be obtained from coordinatesof the at least one surface point provided by the 3D sensor as describedherein.

Aspects of some embodiments of the invention include systems and methodsfor generating a scanning plan. The scanning plan may be for medicalimaging of at least a portion of a patient. In some embodiments, such asystem includes a processor configured to receive input data, andgenerate based on the input data a scanning plan. The input data mayinclude, for example, an indication of a region to be imaged; and dataindicative of the location of at least one surface point located on anouter surface of the portion of the patient to be scanned. The locationof the surface point may be sensed by one or more 3D sensors, asdescribed above. The processor may be configured to generate thescanning plan based on the received information. The scanning plan mayinclude, for example, gantry angles, corresponding dwelling times,swivel angles for each detector, dwelling times corresponding to theswivel angles, a range of gantry angles to be swept continuously, etc,as a function of time, for example a succession of respective dwellingtimes for a sequence of gantry angles and/or a succession of respectivedwelling times for a sequence of swivel angles. Other examples include arange of (gantry and/or swivel) angles and a rate of change for theangles, respective angular trajectories defined by a continuous functionor discrete samples over time. Of course, a scanning plan may compriseany combination of one or more of these ways to define angulartrajectories. More generally, a scanning plan may define respectiveangular trajectories for gantry and/or swivel angles. In someembodiments, the scanning plan uses as additional input the positioningof the patient support. The positioning may be vertical and/orhorizontal. In some embodiments, the processor is configured todetermine the positioning of the bed with respect to the gantry beforeor as part of generating the scanning plan. In some embodiments, asystem for generating a scanning plan includes a gantry, detectors,patient support, and other structural parts related to each other asdescribed above in reference to system 100. In some embodiments, thesystem for generating the scanning plan may include only the processor,with input or inputs to receive the required information and an outputto deliver the scanning plan, e.g., for evaluation by a user or forexecution by an imaging apparatus capable of controlling all the variousparameters to be controlled in accordance with the plan. The system mayalso be composed of the processor and some or all of the parts of system100.

In some embodiments, the planning may be updated during scanning. Forexample, in some embodiments, a preliminary scanning plan may begenerated based on a first point cloud generated by the one or more 3Dsensors. During the execution of the plan, the one or more 3D sensorsmay be exposed to other part of the patient, e.g., because the patientmoved, or because the sensor(s) moved. For example, in embodiments wherethe sensors are mounted on the gantry, changing a gantry angle maychange the body portion exposed to the sensors. In another example,where the sensors are mounted on the extendable arms, taking the armsnearer or further from the patient may expose different portions of thepatient to the sensors. Such further exposure may provide data usefulfor better planning of the scan.

FIG. 8 is a flowchart of a method 800 of planning a scan of a region tobe imaged residing in a portion of a patient by a medical imagingdevice. The medical imaging device may include a support, such as a bedor a couch. The support may be configured to support at least theportion of the patient that has to be imaged. The imaging device mayfurther include multiple gamma detectors facing the support. Thedetectors may be all supported by a gantry, which may be rotatable.

At 802, data pertaining to spatial coordinates of a point of an outersurface of the portion of the patient is received. In some embodiments,the spatial coordinates are of a plurality of points composing a pointcloud indicative of the position of an outer surface of the patient'sportion to be imaged, the support supporting said patient's portion, orboth the patient and the support. For example, in some embodiments, thedata may include coordinates of a plethora of points, forming together apoint cloud that visually resembles the outer surface of the patient'sportion to be imaged, and/or of the bed, on which the patient portion tobe imaged is supported. The data pertaining to the spatial coordinatesof the one or more points of the outer surface of the patient may bereceived from a 3D sensor as described herein. The data may includecoordinates of one point, two points, or more points. For example, thedata may include coordinates of points composing a point cloudindicative of the position of an outer surface of a portion of thesupport and/or patient.

In some embodiments, the data is received from a plurality of 3Dsensors. In such cases, data from different sensors may be combined toprovide a combined point cloud. The combined point cloud may providedata on points from all portions of the outer surface of the patientand/or bed (e.g., if the fields of view of the 3D sensors cover, whencombined, the entire outer surface), or portions thereof (e.g., whenthere are gaps between fields of view of adjacent sensors). The receiveddata may be indicative of the spatial coordinates of the surface pointsin the coordinate system of the medical imaging device, or in some othercoordinate system that can be registered to the coordinate system of themedical imaging device. In the latter case, the method may include astep of registering the data to the coordinate system of the device.This step may include, in some embodiments, calibration of the system.Combining data sets received from different 3D sensors may be carriedout after this registration or calibration. For example, the sensors maybe calibrated each to its own coordinate system, e.g. the received pointcloud is in units of mm with regard to an arbitrary coordinate system,as determined by the sensor manufacturer. In such cases, a systemiccalibration may be performed, where several calibration objects areplaced in known locations within the coordinate system of the scanningsystem. The calibration objects may be imaged by each sensor, and thelocation may be detected within the sensor's coordinate system. Once thelocation of the calibration objects is known in the sensor coordinatesystem, a transformation between the coordinate system of the 3D sensorand that of the scanning system may be determined. This transformationmay be a rigid transformation. Each time the sensor is used duringnormal operation, the coordinates provided by the sensor may betransformed to the scanning system coordinates using the saidtransformation. In some embodiments, the calibration may be repeated atdifferent sensor locations, e.g., at different gantry angles. In someembodiments, one calibration is used, and the calibrated coordinates aretransformed to reflect the movement of the sensors.

In some embodiments, based on the data pertaining to the coordinates ofthe surface points, a non-diagnostic scan may be planned, for example,as described herein. The non-diagnostic scan is then carried out.

At 804, the non-diagnostic radiographic image of the portion of thepatient is received. The dimensionality of the radiographic image may bethe same as the dimensionality of the image to be taken. For example, ifthe image to be taken is planar, so is the non-diagnostic radiographicimage; and if the image to be taken is 3D, so is the non-diagnosticradiographic image. The non-diagnostic radiographic image may be, forexample, a planar view of a certain plane in the patient's portion to beimaged, or a 3D image having a low signal to noise ratio. Thenon-diagnostic image may be of the patient's portion to be imaged. Thenon-diagnostic image may include the region to be imaged and itsimmediate surrounding. The non-diagnostic image may be acquired by lessthan half a time that an image of diagnostic quality may be acquired.For example, the non-diagnostic image may be acquired in less than 10minutes, for example, in one or two minutes.

At 806, an indication of a region of special interest is received. Theindication may be put in by a user, of example, by marking a region on adisplay of the non-diagnostic image.

At 808, a diagnostic scan is planned based on the location of the regionof special interest, and the data pertaining to coordinates of thesurface points. For example, in some embodiments, collecting gammaphotons is planned to take place from every point within the outersurface; but the plan may include devoting more time to collecting gammaphotons emerging from the region of special interest than from otherregions that are to be scanned. Thus, longer dwelling times may beassociated in the scanning plan to swivel angles at which a detector isaimed at the region of special interest than in other swivel angles. Insome embodiments, however, some time is devoted to collecting photonsemerging from points outside the region of special interest to allow amore accurate reconstruction of the image.

More generally, the scanning plan may include any parameter that mayaffect the arrangement of the detectors in respect of the region to beimaged, such as vertical positioning of the bed in the gantry,horizontal positioning of the bed in the gantry, gantry angles to beused, and swivel angles to be used. In some embodiments, the plan mayalso include timing instructions, for example, the dwell time for eachdetector at each swivel angle and the dwell time of the system at eachgantry angle. One, some, or all of these may be determined so as tomaximize image quality while minimizing imaging time, taking intoconsideration the exact position of the region of special interest, asrevealed from the marking made on the non-diagnostic image, andconstraints originating from the location of the outer surface of thepatient, as revealed by the one or more 3D sensors.

It is expected that during the life of a patent maturing from thisapplication many relevant systems and methods will be developed and thescope of the term image, scanning, and directable detector is intendedto include all such new technologies a priori.

As used herein the term “about” refers to ±10%.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a processor” or “at least one processor” may include aplurality of processors, separated from each other or interconnected inany conceivable form.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

The invention claimed is:
 1. A method of imaging a region of interest ina patient by a medical imaging device for imaging a patient supported bya patient support, the medical imaging device comprising a 3D sensor, agantry and a plurality of gamma detectors supported on the gantry, themethod comprising: receiving an indication of the kind of image to betaken; receiving 3D sensor coordinates from the 3D sensors of at leastone point of an outer surface of the patient, the patient support, orboth the patient and the patient support; determining at least oneparameter affecting an arrangement of the gamma detectors in respect tothe region of interest, the at least one parameter comprises a pluralityof gantry angles, based on the indication of the kind of image and the3D sensor coordinates of the at least one point; and controlling thegamma detectors, the gantry, and/or the patient support in accordancewith the at least one parameter determined.
 2. The method of claim 1,wherein the at least one parameter comprises a position of the patientsupport in respect to the gantry.
 3. The method of claim 1, furthercomprising determining, based on the indication of the kind of image tobe taken and the 3D sensor coordinates of the at least one point, adwelling time for each of said plurality of gantry angles.
 4. The methodof claim 1, wherein the at least one parameter comprises a range ofgantry angles.
 5. The method of claim 4, further comprising determining,based on the indication of the kind of image to be taken and the 3Dsensor coordinates of the at least one point, a pace for moving thegantry along the range of gantry angles.
 6. The method of claim 1,wherein each of said gamma detectors is mounted on an arm extendablefrom the gantry.
 7. The method of claim 1, wherein each of said gammadetectors is mounted on an arm extendable from the gantry so that eachgamma detector may swivel in respect to the arm.
 8. The method of claim7, wherein the at least one parameter includes a swivel angle of thegamma detector in respect to the arm for at least one of the gammadetectors.
 9. The method of claim 8, wherein the at least one parameterincludes a plurality of swivel angles of the gamma detector in respectto the arm for at least one of the gamma detectors.
 10. The method ofclaim 8, wherein the at least one parameter includes a range of swivelangles of the gamma detector in respect to the arm for at least one ofthe gamma detectors.
 11. The method of claim 10, further comprisingdetermining, based on the indication of the kind of image and the 3Dsensor coordinates of the at least one point, a pace for moving thegamma detector along the range of swivel angles.
 12. The method of claim1, wherein the at least one parameter includes an amount of extension ofat least one extendable arm connecting a gamma detector to the gantry.13. The method of claim 1, further comprising generating, based on the3D sensor coordinates of the at least one point, a model of the outersurface of the patient, the patient support, or both the patient and thepatient support, and determining the at least one parameter based on alocation of the region of interest in respect to the model.
 14. Themethod of claim 13, comprising determining the at least one parameteraffecting the arrangement of the gamma detectors in respect to theregion of interest based on a location of the region of interest inrespect to the model of the outer surface of the patient and/or patientsupport.